This book is based on a project to completely annotate what is known about the function of the ~150 genes encoded by the genome of the most commonly investigated baculovirus, AcMNPV. Once the annotation was completed (summarized in Chapter 12), the material was organized into a series of chapters integrating the role of the gene products in the biology of major processes central to the replication and pathology of baculoviruses. Chapters on taxonomy, the application of baculoviruses as insecticides, the molecular basis for the remarkable ability of these viruses to express genes at high levels, and the interrelationships of baculovirus and insect retroviruses are also included. The chapters are accompanied by 41 figures, 14 tables and a glossary of common terms used in baculovirology.